The use of nano-particle additives has been driven in many ways, either by processing or chemical treatment in the attempt to uniformly distribute the particles throughout the polymer in order to obtain a uniform material with homogenous properties. In some specific instances the processor, tries to obtain spatial localization of nano-particle fillers within the material, as is the case with many electronic nano-composites. Nanoclays and other additives such as carbon nanotubes are most often treated or processed for maximum dispersion.
Exfoliated clays have a variety of applications. One application of these clays is in polymer clay nanocomposites. These clay nanocomposites are polymer matrices containing platelet shaped clay particles that have sizes of a few nanometers thick. Because of their high aspect ratios and their high surface area, clay can import unique combinations of physical and chemical properties to make the polymer.
The clay particles used in nanocomposites occur naturally as layered silicates. In order to obtain the benefits of the clay particles, the clay particles are preferably exfoliated, i.e. delaminated and uniformly dispersed in the polymer matrix.
When clay is blended with a polymer, one of the problems that can be encountered is the incompatibility between the hydrophilic polymer and the hydrophilic clay particle surface. As a result of this incompatibility, there is a risk that the exfoliated clay particles do not remain exfoliated and it can be difficult to achieve a uniform dispersion of the clay particles throughout the blend. To solve this problem, clays have been treated with an organic compound to create an organoclay. An organoclay has an organic material bonded to a surface of the clay particle that permits the clay particle to remain exfoliated and enhances the blending of the hydrophilic clay in the hydrophilic polymer. The bonding of the organic material to the clay to produce the organoclay requires a number of steps in the process. One type of material that has been used to form the organoclays has been an ammonium compound such as a quaternary ammonium compound. In order to form the organoclays with quaternary ammonium compound, the quaternary ammonium compound is grafted to the clay particles.
While grafted polymers onto clay particles has aided exfoliation of clay particles, it does not typically provide complete exfoliation. As a result, there is a need for an improved process of exfoliating clays.